BMC digging deep to give Mumbai additional water

Come August and a lot of hard work that the engineers of the Brihanmumbai Municipal Corporation (BMC) have put in, unnoticed by most of us, would finally bear fruit.

The master plan to enhance supply of water to the sprawling metropolis is now in its final stages and it is expected that 450 million litres per day (MLD) will be added.

While 3,500 million litres of water is supplied to the city every day, the total demand for water is around 4,200 million litres daily.

According to additional municipal commissioner Dr Sanjay Mukherjee, the extra 450 MLD of water will come from five state-of-art infra projects implemented by the civic body. The projects include lake-tapping of Modak Sagar, installing recycling plants at the Bhandup and Panjrapol water complexes, establishing underground tunnel systems (Gundavli to Kapurbawdi to Bhandup) and by systematically improving the existing water distribution network in catchment areas.

Lake-tapping at Modak Sagar in Thane is the first-ever carried out in the nation and third of its kind in the world. With assistance from hydraulic engineers who were behind the success of Koyna Dam, the civic body aggrandised the capacity by 30,000 million litres, which amounts to almost nine days of water supply to the city. The cost of the project is Rs222 crore.

"Increasing the intake level was imperative for better force of water supply in the city," explained AS Tawadia, HOD of hydraulic engineering department. He added that tapping has boosted the overflow level of the lake, which is 163 metres and the usable content today is about 1.29 lakh million litres.

Another part of the plan is to start two water treatment plants. By the end of October, BMC's much-delayed plan to add a supply of 115 MLD water, will soon start operations. Its two main water treatment plants at Pise Panjrapur and Bhandup, which waste 50 MLD of water each, will now provide additional water to Mumbai.

"The Bhandup treatment plant has already been restructured and is adding 50 MLD of water to the city's supply, whereas the Pise Panjrapur plant is nearing completion," deputy municipal commissioner (special engineering) Ramesh Bamble said.

The third move to quench the thirst of teeming Mumbai was the completion of the first phase of the 6.8km Gundavali to Bhandup Complex underground tunnel in record time. With this the BMC can transfer water from the newly-constructed Middle Vaitarna dam to the city. By the end of this financial year, the corporation envisages to complete the second phase of the 15km-long project.

The Middle Vaitarana dam project consisted of constructing two underground tunnels — from Gundavali to Kapurbavdi (Phase I) and from Kapurbavdi to Bhandup Complex (Phase II). The cost of both the tunnels is Rs2887.26 crore.

The 6.8km Gundavali to Kapurbavdi tunnel work began in November 2009 and was completed in 2014. The work on the Phase II is has touched 85 per cent completion and the remaining work will be completed by October.

The tunnels have a capacity to carry 4,000 MLD water. It would also be used to carry water supply from proposed Gargai and Pinjal dams in the next couple of months.

With water leakage currently at anything between 700-900 MLD every day, the BMC plans to shift gears on the issue. To detect leaks in its pipelines, a new technology — Helium gas detection powered by GIS mapping — will be employed.

The new technology will involve the use of a sound unit, including an amplifier, that will be placed on the road. The machine will then mute all background noise, and capture only the sound of water flow.

"The sound will be amplified and one can easily detect if the water is not flowing smoothly and the pipe has a leak," said Bamble. A pilot project is being monitored in two wards — Bandra and Malad.